In wireless communication devices, radio frequency (RF) power amplifiers (PAs) are often used to provide transmit signals at increased power levels needed for operation within a communication system. For example, cellular telephone devices use PAs to transmit signals at power levels needed to communicate effectively with cellular base stations. In addition, these transmit power levels must often be regulated by the communication device. In prior communication devices, an RF coupler has been used to split off a proportional part of the transmit output signal so that the transmit output power can be monitored by the system.
FIG. 1 (Prior Art) is a block diagram for an embodiment 100 including an RF coupler 106 and power amplifier (PA) integrated circuit 104 for transmission of signals in a wireless communication system. As depicted, a transceiver or baseband integrated circuit (IC) 102 sends a transmit (TX) signal 114 to the PA integrated circuit 104. The integrated circuit 102 is also configured to provide a transmit power (TX PWR) control signal 123 to the CMOS PA 104. The CMOS PA 104 in turn provides an amplified signal 118 to a radio frequency (RF) coupler 106. The RF coupler 106 operates to send the transmit signals 120 on to a duplexer 108, which in turn sends and receives signals to and from the switch (SW) 110 and the antenna 112. In addition to sending transmit signals 120 to the switch (SW) 110, the duplexer 108 also communicates receive (RX) signals 116 back to the transceiver/baseband IC 102. In addition to passing along the transmit signals 120 to the duplexer 108, the RF coupler 106 also sends back to the transceiver IC 102 a direct RF signal (DIRECT RF) 122 having power proportional to the transmit output power. The transceiver IC 102 utilizes this RF signal (DIRECT RF) 122 as a feedback RF signal to monitor and determine transmit output power settings and other operational details related to the transmit operations of the communication device. Thus, the transmit power (TX PWR) control signal 123 from the integrated circuit 102 is at least in part dependent upon this feedback RF signal (DIRECT RF) 122 from the RF coupler 106.
In many communication devices, such as cellular telephone devices, it is desirable to reduce the size required on a printed circuit board (PCB) to mount all of the components and integrated circuits (ICs) needed to implement the communication device. To achieve a reduced form factor, some solutions have combined a PA packaged IC device and an RF coupler (CPLR) packaged IC device into a multi-chip module (MCM).
FIG. 2 (Prior Art) is a diagram for a MCM 200 that includes a PA 104 as a first packaged IC device and a coupler (CPLR) 106 as a second packaged IC device. As stated above, the transmit (TX) signal 114 is received by the PA 104, and an amplified signal 118 is then provided to the coupler (CPLR) 106. The coupler (CPLR) 106 transmits the output signal 120 and sends back the RF signal (DIRECT RF) 122 that is used by the transceiver IC 102 to monitor transmit operations. For the MCM 200, the PA 104 and the coupler (CPLR) 106 are separate monolithic IC device packages that are mounted onto each other to make a combination device. In this way, the MCM 200 requires a smaller area on a PCB than would be required for separately mounting a PA and an RF coupler on the PCB.
For many communication devices, however, further reduction in the surface area and space required for the PA/coupler utilized by these communication devices is desirable.